Orthopaedic surgical procedures often involve the use of a fixation device. Usually an access hole is produced in a bone or soft tissue wherein a suitable fixation device can be fastened. Apart from screws, expandable fixations devices can be used which are inserted into the hole in a collapsed state and transformed into an expanded state once being correctly positioned.
In one example orthopaedic surgical procedure, such as a lumbar microdiscectomy, radiculopathy is treated by surgically removing the herniated nucleus pulposus to achieve neural decompression. The lumbar microdiscectomy is one of the most common spinal surgeries performed today. Many patients find relief with this procedure, but for others, the disc could re-herniate through the opening in the annulus resulting in continuing pain and potentially requiring additional surgery. Currently, the standard microdiscectomy technique does not involve closing the annular defect and presents the surgeon with a dilemma. The surgeon may elect to remove the herniated portion of the nucleus impinging on the nerves, which treats radiculopathy, but may increase the risk of post-operative reherniation of the remaining nucleus through the existing defect of the annulus. Alternately, the surgeon may elect to perform extensive debulking, in which most of the remaining nucleus material is removed in addition to the herniated portion to minimize the risk of post-operative reherniation. However, the risk of post-operative disc height collapse and subsequent progression to lower back pain increases.
Conventional expandable implants include a sleeve with an expandable portion having plurality of fingers or expandable parts formed by intermediate slots or holes in the peripheral wall of the sleeve and a compression element extending through the central bore of the sleeve. The compression element can be coupled to the front end of the sleeve so that upon pulling said compression element towards the rear end of the sleeve said fingers or expandable parts are bent radially outwards so as to transform said expandable portion from its collapsed state to its expanded state.